He traveled to Los Angeles and trained at the local NJPW dojo.[5] He debuted for the promotion in a match against Wataru Inoue at the Korakuen Hall on October 12, 2002.[5] He started out working on the lower card to gain experience. He lost to Ryusuke Taguchi on December 27, 2003 in a chance to compete at the January 4 Dome Show. He defeated Hirooki Goto, Aikya Anzawa, and Hiroshi Nagao in the 2004 Young Lion Cup and earned six points but it was not enough to qualify in the finals.[6][7][8] Yamamoto also competed in the 2005 Young Lion Cup where he only won one match when he defeated Yujiro.[9] In 2006, he competed in his first G1 Climax tournament but lost all four matches.[10] He competed and teamed with Manabu Nakanishi in the 2006 G1 Tag League and they defeated Giant Bernard and Travis Tomko to earn their only win in the tournament.[11] During the Summer of 2007, he teamed with Hiroshi Tanahashi in a team called "New Japan Dragons" in a number of matches. Yamamoto and Tanahashi challenged then-champions Bernard and Tomko for the IWGP Tag Team Championship but lost.[12] His last match in NJPW was on November 2, 2007 where he teamed with Yuji Nagata against Tomohiro Ishii and Toru Yano but they lost the match.[13]

Yamamoto joined the WWE in late 2007 and debuted for WWE's developmental territory, Florida Championship Wrestling (FCW), where he was to undergo assessment and training in the "WWE Style" of wrestling which is different from the Japanese style. He first wrestled under the name, Mr. Yamamoto and then simply as Yamamoto. He also briefly teamed with Sheamus O'Shaunessy where they formed a tag team under the name, The Movers and the Shakers. He later changed his ring name to Yoshitatsu and tweaked the spelling of it to Yoshi Tatsu, which is the name he currently wrestles under.

On June 30, 2009, Tatsu joined the ECWbrand and debuted under the ring name, Yoshi Tatsu which he joined because of their new superstar initiative.[14] In his first match on the brand that night he defeated Shelton Benjamin but he lost a rematch to Benjamin on the July 9 episode of ECW.[15] On the October 20 episode of ECW, Tatsu was involved in a number one contender's match for the ECW Championship against Zack Ryder who he defeated to become the number one contender for the title.[16] He was unable to win the championship the next week against Christian who was champion at the time.[17]

On the December 22 edition of ECW, Tatsu had a match against Jack Swagger who he defeated to earn a spot in the ECW Homecoming battle royal where the winner would challenge Christian for the ECW title at the Royal Rumble.[18] He didn't win the battle royal however and was eliminated by Kane. Tatsu competed in his first Royal Rumble but lost when he was eliminated John Cena. Tatsu also formed a tag team with Goldust and they became the number one contenders for the Unified WWE Tag Team Championship but they lost in their championship match against The Miz and Big Show on which was the final episode of ECW on Syfy.[19]

Yoshi Tatsu was announced as a pro for 5th season of NXT Redemption where he trained Byron Saxton who was a competitor on NXT season 4.[25] On the April 26 episode of WWE NXT, Byron Saxton started a feud with Tatsu after he attacked him when Tatsu cost Saxton his match against Lucky Cannon.[26] On the May 31 episode of WWE NXT, Saxton was the second rookie eliminated.[27] After Edge was forced to retire due to a neck injury he gave up the World Heavyweight Championship and they had a 20-man battle royal to determine who the #1 contender was going to be to face Alberto Del Rio in a ladder match at Extreme Rules which Tatsu was a part of. Tatsu was eliminated by Christian.[28] Tatsu also participated in a Smackdown vs. Raw battle royal during the 2011 WWE Draft but was eliminated by the Big Show.[29]

Tatsu was drafted to the SmackDown brand as part of the 2011 Supplemental Draft on April 26.[30] He appeared at Extreme Rules on May 1 at where he was a Lumberjack in the WWE Tag Team Championship match. On the June 3 edition of SmackDown, He made his debut for the brand in a losing effort against Jinder Mahal.[31] After the match, Mahal instructed The Great Khali to attack Tatsu and apply the Vise Grip on him.[31] On the July 26, 2011 episode of NXT, Tatsu defeated Tyson Kidd in the first Necklace on a Pole match.[32] After the match Kidd brutally attacked the right leg of Tatsu and on the August 2nd edition of NXT, Kidd said that "there will be no more Yoshi Tatsu".[32]

Tatsu made an appearance on the August 19 episode of SmackDown, where he competed in a 20-man Over The Top Rope Battle Royal to determine the No. 1 Contender for the World Heavyweight Championship. Tatsu was eliminated by the winner, Mark Henry. He returned to NXT on the September 6th episode and debuted a new dark look with a half face paint and a black ring attire.[34] He stopped wearing the facepaint by October of 2011. He would go on to form an alliance with Trent Barreta and they feuded with Curt Hawkins and Tyler Reks. Tatsu competed on the January 27th edition of Smackdown, teaming with Santino Marella in a losing effort to the WWE Tag Team ChampionsPrimo and Epico.[35] At the Royal Rumble, Tatsu defeated Heath Slater in the dark match.[36]